Abstract ID: 629

Vulnerability of Amazonian riparian forest to the climate changes

Global climate change and regional deforestation may lead to rainfall reduction in the Amazon Basin. Resilience against drought may be high at low to moderate disturbance, but very low at strong disturbance. Assuming that large parts of the Amazon forest landscape, particularly in the central region, is fairly resilient against climate change stress because of the variability in water supplies within the landscape as controlled by topography. To what extent this applies depends on the degree to which valley vegetation is nutrient-limited or disturbed by human-induced land-use changes. Drought sensitivity of valley areas is investigated by observations of soil respiration, decomposition of organic matter, groundwater chemistry and water table control. The effect of lowering the water table provokes a diminishing of -30% of rainfall at saturated valley soils (riparian zone) which was installed a drainage experiment. Emissions of soil respiration were ~4.5 µmol m^-2s^-1 before the drainage experiment for both control and drainage area. After 8 months of this artificially drainage experiment, control area had similar emissions as before. The opposite happened in the drainage area, after 8 months the emission decreased to ~2.0 µmol m^-2s^-1 in 11 months. These results show strong correlations with groundwater chemistry at the drainage area. These findings suggest that the ecosystem is vulnerable to global warming effects, such as a decrease of rainfall and it is possible that the riparian areas of central of Amazon region will change soil carbon stock and also losing of richness adapting more the vegetation to a dry sand soil/areas and poor soils as a Tall Heath Forest (Campinarana).

Session:  Biogeochemistry - Floodplain ecosystem processes.

Presentation Type:  Poster